print-dispatcher.php

<?php
/**
 * Create a PULL socket to receive print requests from the webserver.
 * Create a PUB socket to send print requests to the windows laptop.
 */
$context = new ZMQContext();
$pub = $context->getSocket(ZMQ::SOCKET_PUB);
$pub->bind('tcp://*:5566');
$pull = $context->getSocket(ZMQ::SOCKET_PULL);
$pull->bind('tcp://*:5567');

while (true) {
    $printJob = $pull->recv();
    $pub->send($printJob);
}

print-receiver.php

<?php
/**
 * Receive a print request and print.
 */
$context = new ZMQContext();
$sub = $context->getSocket(ZMQ::SOCKET_SUB);
$sub->setSockOpt(ZMQ::SOCKOPT_SUBSCRIBE, '');
$sub->connect('tcp://server:5566');

while (true) {
    $printJob = $sub->recv();
   
    $html = file_get_contents($printJob);
    $file = get_temp_dir() . '/printJob_' . sha1($html) . '.html';
    file_put_contents($file, $html);

    // http://windowsitpro.com/systems-management/how-can-i-print-usb-printer-command-prompt
    exec('print /d:LPT2: ' . $file);
}

print-requester.php

<?php
/**
 * Send a print request to the print-dispatcher.
 */
$context = new ZMQContext();
$push = $context->getSocket(ZMQ::SOCKET_PUSH);
$push->connect('tcp://server:5567');

$push->send('http://server/sale/receipt/' . $receiptId);